Abertella gualichensis Martínez et al., 2005

Figures 1, 4.

2005 Abertella gualichensis Martínez et al.: 1230–1232, figs. 2–3.

Diagnosis. Abertella with pronounced, marginally-directed, curved extensions of oral ambulacral plates joining proximal edges of first interambulacral postbasicoronal plates in posterior interambulacrum; posterior notch shallow but acute; paired interambulacra narrower, than in other Abertella, not narrowing near the ambitus. Type material studied. Holotype MACN-Pi 4714, paratypes MACN-Pi 4705, 4706, 4709. Description. See Martínez et al. (2005).

Occurrence. A. gualichensis is recorded only from the earliest middle Miocene of Salina del Gualicho, Río Negro Province, Argentina in the lower part of the Gran Bajo del Gualicho Formation (Fig. 1).

Remarks. In the original description, A. gualichensis was distinguished from other Abertella largely by its broad but shallow posterior notch and its relatively narrow, non-alate test compared to other members of the genus. In addition, the separation of the oral interambulacral postbasicoronals from the basicoronal plates is less pronounced in A. gualichensis than in most other Abertella, with the exception of A. pirabensis, and the oral interambulacra of A. gualichensis do not widen and then markedly attenuate as they approach the ambitus.